Patent GB-780580-A (GB)
Title: Method of interrupting the formation of transverse rents in paper webs and apparatusfor carrying said method into effect
IPC: D21F7/04
Filed: 1954-03-30
Abstract: 780,580. Photo-electric control of rents in paper webs. PROFFEN, H. March 30, 1954 [March 30, 1953], No. 9298/54. Class 40 (3). [Also in Group VIII] A method of intercepting transverse rents in webs of paper during manufacture and of subsequently again feeding a full width web comprises using two radiation-sensitive cells disposed to receive beams projected from respective emitters on to the paper when a rent intercepts the beam and operate through amplifiers respective intercepting devices which limit the extent of the rent by cutting or perforating it. The intercepting devices are movable across the web and in the rest position are disposed on opposite sides of the web centre line and the emitters are disposed so that their beams impinge on opposite sides of this line. The intercepting device on one side of the line is operated in response to the beam impinging on the opposite side of the line and each intercepting device is then moved towards the side of the web from which the rent started. Transference of a web of paper 24 from suction roller 1 to a driven felt band is liable to start transverse rents from either edge of the web. Light from sources 5, 6 which is beamed on photo-cells 7, 8 respectively is normally blocked by the web. The apparatus is prepared for operation by closing switches 39, 40 (Fig. 4). The armatures 35, 36 of relay coils 33, 34 in the anode circuits of valves 31, 32 the grid circuits of which include the respective photo-cells are normally held by their coils so that glow lamps 37, 38 are lit. When, for example, a rent developing from the left-hand side of the web (Fig. 1) intercepts the beam of light from source 5 cells 7 is illuminated thereby cutting off valve 31 and releasing armature 35 to complete an energizing circuit for relay 41 through the contacts 44, 45 of relay 47 which is then locked in its inoperative condition by the separation of contacts 52, 57. Solenoid 60 operating the valve supplying nozzle 13 is energized via contacts 52, 53 and the resulting fluid jet forms a longitudinal slit in the web as it passes which intercepts and diverts the developing rent. Counter 98, indicator 99 and warning bell 100 are also operated and an energizing circuit for motor 75 is prepared through the contacts of limit switch 68. An adjustable time delay relay 63 is energized via contacts 54, 55 and 61, 62 to complete a circuit for motor relay 71, through contacts 64, 65 the contacts of the motor relay completing an energizing circuit for motor windings 78, 82-83 causing it to drive anticlockwise. Relay 71 also completes a holding circuit for relay 41 through its contacts 69, 86. The nozzle 13 which is inclined to the plane of the web and which, together with nozzle 14 is driven by the motor through the endless belt 18 is thus moved to the edge of the web from which the rent started, so as to cut it out and restore the web to its original width. Toggle-jointed pipe 22 supplying fluid to the nozzle also serves to rotate it as it traverses the web so as to produce a smooth cut. When the nozzle reaches the web edge limit switch 59 is closed and limit switch 68 opened to break the holding circuit of relay 41 thereby closing the valve supplying nozzle 13. Relay 71 drops to open-circuit the motor. The time-delay relay 90 is now energized via the normally closed contacts 54, 56 of relay 41 and the contacts of the limit switch 59. Relay 81 is in turn energized to complete a circuit for the windings of motor 75 to drive it clockwise thereby restoring the nozzles to their original positions whereupon switch 59 is opened causing relay 81 to drop. Response of the system to interception of the beam from source 6 by rents starting from the opposite side of the web is essentially the same except that the functions of relays 47 and 41 are interchanged and that the valve to nozzle 14 is opened instead of that to nozzle 13. The nozzles may be replaced by mechanisms including knives with fixed or rotating blades. Method of starting a new web.-The machine is started and switch 89 turned to its second operative position causing motor 75 to drive the nozzles 13 and 14 to their extreme positions without discharging fluid. The switch is then moved via the third position to the fourth causing the nozzles to move inwards. When they have moved a short distance the switch is moved into the fifth position causing the nozzles to remain stationary with nozzle 13 discharging fluid on the moving web to separate a narrow strip which is led on to the felt band. The strip is then widened to the full web width by (a) moving the switch to its sixth position to cause the nozzles to move in with nozzle 13 discharging; (b) when the nozzles reach the centre of the web turning the switch to the seventh position to turn nozzle 14 on and 13 off with the nozzles fixed; and (c) moving the switch to its eighth position to move the nozzles outwards as 14 discharges. The switch is then put in the eight position to drive the nozzles back to their normal position without discharging.